Über die phytotoxisch wirkenden Stoffe aus Brachycaudus napelli Schr.

V. Kazda

Biologia plantarum 1968, 10:1 | DOI: 10.1007/BF02920736

Im Wasserextrakt der zerriebenen BlattläuseBrachycaudus napelli Schrk. befinden sich phytotoxische Stoffe, die durch einen biologischen Tomatensprosstest untersucht werden können.
Bei Erwärmung der Aphidenextrakte von 125°C sowie bei zweistündiger Erwärmung der getrockneten Rückstände bei 105°C blieb die Phytotoxizität von denselben unverändert erhalten.
Die phytotoxischen Stoffe sind aus dem Aphidenhomogenat sehr gut mit Wasser, gut mit Äthanol und Azeton, dagegen gar nicht mit Diäthyläther, Benzol und Chloroform bei Zimmer-temperatur extrahierbar.
Durch Dialyse wurde aus dem Blattlausextrakt eine kleinmolekulare Fraktion abgetrennt,...

The temporal course of fertilization and localization of starch in the barley pistil

Mária Luxová

Biologia plantarum 1968, 10:10 | DOI: 10.1007/BF02920737

The time course of fertilization in barley is described and the observations compared with those of older authors. The triple fusion is terminated in spite of its late onset always before syngamy. Whereas the time period reported for the so-called preparatory phase of fertilization and for the division of the primary endospernal nucleus is similarly reported by many authors, there are difference of as much as 8 hours in various report on the beginning of the division of the zygote (beginning of the prophase 13-21 hours after fertilization). In the present material, the zygote began to divide latest.
The transient reserve substance representing an...

Effects of podophyllin and 8-hydroxyquinoline on meiosis

Soheir M. Amer

Biologia plantarum 1968, 10:15-19 | DOI: 10.1007/BF02920738

The induced meiotic abnormalities as a result of sprayingVicia faba plants with aqueous saturated solutions of podophyllin and 8-hydroxyquinoline were studied. The 2 drugs induced the same types of abnormalities including lagging chromosomes, stickiness, and bridges. The main difference between the 2 agents was the induction of polyploid P.M.Cs. by 8-hydroxyquinoline.

Zellsaftbrechungsindex bei Winterweizensorten in Beziehung zur Frostresistenz im Zeitabschnitt Winter - Frühling

C. T. Horovitz

Biologia plantarum 1968, 10:20 | DOI: 10.1007/BF02920739

Bei 14 Winterweizensorten wurde im Zeitabschnitt Winter-Frühling der Zellsaftbrechungsindex gemessen. Die höchsten Werte wurden bei einigen frostresistenten, die niedrigsten Werte bei nichtresistenten Sorten gefunden, der Zellsaftbrechungsindex war aber nicht in allen Fällen der Frostresistenz proportional. Mit Rücksicht auf Stoffwechselvorgänge der osmotisch aktiven Stoffe, die deren Menge und Verhältnis bestimmen, sind Saisson- sowie Tagesveränderungen im Laufe von Winter und Frühling nicht nur von der Temperatur und Feuchtigkeit der Umgebung abhängig. Der Zellsaftbrechungsindex unterliegt verschiedenen Veränderungen in Beziehung zu Pflanzenernährung...

Effect of age on water loss of leaves

J. Pazourek

Biologia plantarum 1968, 10:27 | DOI: 10.1007/BF02920740

The water loss of leaves of the same level of insertion but of various ages was examined. The results show that the transpiration of youngest leaves is higher than that of the older ones. The oldest leaves which have started yellowing show an increase of transpiration. This is probably related to the premortal changes of the leaf. The differences are probably caused by various physiological states of leaf because the leaf area was not different.

A virus of tobacco rattle group naturally occurring inPlantago sp. in Czechoslovakia

Z. Polák, O. Králík, M. Cech

Biologia plantarum 1968, 10:31 | DOI: 10.1007/BF02920741

The Czechoslovak isolate produced symptoms characteristic for viruses belonging to the rattle group. A virus variant comparable to Köhler's "Wintertyp" appeared to be present. Two predominant particle lengths of 90 and 191 nm were found in purified preparations. The virus reacted with Dutch TRV antiserum.

Morphactin-gibberellin interaction in lettuce seed germination and seedling growth

Daksha Sankhla, N. Sankhla

Biologia plantarum 1968, 10:37 | DOI: 10.1007/BF02920742

Morphactin-butylester (a flourene-9-carboxylic acid derivative) inhibited seed germination of two strains of lettuce. Morphactin induced inhibition of germination could be partially or wholly reversed by simultaneous addition of gibberellic acid. However, gibberellic acid played very little part in reversing the inhibitory effect of morphactin on seedling growth. It is concluded that gibberellin can not reverse all the growth effects induced by morphactin.

Growth effects of 2-thiouracil and possibility of selective inhibition of floral differentiation inChenopodium rubrum L.

Frideta Seidlová, J. Krekule

Biologia plantarum 1968, 10:41 | DOI: 10.1007/BF02920743

The effect of 2-thiouracil on vegetative growth and floral differentiation was investigated inChenopodium rubrum plants grown in water cultures. Between the low concentrations of the agent, stimulating vegetative growth and floral differentiation, and those inhibiting both these processes, a narrow concentration range was found (1.10^-5 m to 2.10^-5 m), where growth was inhibited selectively. At a concentration of 1.10^-4 m a selective inhibition of development was found when 2-thiouracil was applied at the beginning of photoperiodic induction. Inhibition of development was strong regardless of whether 2-thiouracil...

Comparative transmission of pea mosaic virus by one strain of Myzus persicae Sulz. and two strains of Acyrthosiphon pisum Harris

B. A. Kvíčala

Biologia plantarum 1968, 10:51-57 | DOI: 10.1007/BF02920744

Experiments were conducted to compare the efficiency of transmission of a strain of pea mosaic virus (PMV) isolated in Czechoslovakia by two strains (clones) of the pea aphidAcyrthosiphon pisum Harris (green and red) and one strain ofMyzus persicae Sulz. PMV is a nonpersistent virus and the preliminary fasting of aphids before acquisition feeding increases the efficiency of aphids in transmission of this virus. In our experiments two hour fasted individuals were used and two periods of acquisition feeding on the source (1 and 5 minutes). On the healthy test plants the aphids were left over night. As the source and test plants pea (Pisum...

On the catabolic pathways of sugars in green algae

J. Dvořáková-Hladká

Biologia plantarum 1968, 10:58 | DOI: 10.1007/BF02920745

Respiratory metabolism of the cultures of algaeChlorella pyrenoidosa (82) andScenedesmus obliquus (125) was investigated. One part of algae were cultivated on a mineral nutrient solution, another two parts on the solution with glucose and on the solution with glucose and yeast decoction. Individual steps of respiratory metabolism-endogenous as well as in the presence of exogenous sugars-were estimated according to the response to the following inhibitors: monoiodacetate, NaF, NaN₃, and 2,4-DNP. In the last two cases, fructose, glucose-6-phosphate and fructose-1,6-diphosphate were applied in parallel for comparison. Na-monoiodacetate...

Anaerobic respiration in latex of Hevea brasiliensis substrate and limiting factors

J. Tupý, W. L. Resing

Biologia plantarum 1968, 10:72 | DOI: 10.1007/BF02920746

The site of anaerobic respiration in the latex is the serum. The main respiratory substrate is fructose. The CO₂ formation in serum is increased by additional fructose on the average about 2.5-3 times. Glucose does not influence CO₂ evolution by serum but slightly increases O₂ consumption.
With respect to sugars, latex serum contains essentially only sucrose and a low amount of raffinose. During the incubation of serum sucrose is hydrolysed, the fructose component is immediately utilized in respiration and glucose accumulates.
The rate of CO₂ formation in latex as influenced by fructose is negatively...

Virus like particles in Ficus elastica Roxb.

J. Smolák, J. Brčák

Biologia plantarum 1968, 10:81-83 | DOI: 10.1007/BF02920747